Sensor grid for an electromagnetic digitizer tablet

摘要

A digitizer tablet (10) having an array of conductors that define a sensing plane (12) for sensing an electromagnetic signal generated by a pointing device (16) disposed external to the plane. The tablet includes circuitry, coupled to the array of conductors, for determining a magnitude of an electrical signal or signals induced within the array of conductors by the pointing device. The tablet also includes a data processor (30) that is responsive to the determined magnitude for accurately estimating both a position and an angular orientation of the pointing device relative to a coordinate system associated with the sensing plane. The array of conductors is comprised of an x-axis sensor array (14a) and a y-axis sensor array (14b). Each sensor array includes a plurality of differentially interconnected and overlapping coil pairs. Each coil of a coil pair includes a major loop having auxiliary loops coupled to each end thereof for compensating for unmeasured magnetic fields beyond an end of the coil.